We like The Door buzzer sound circuit, in two-tone sound. It uses a low voltage, 6V power supply so it is safer than general AC main. We can install the push button outdoor, do not worry about rainy to makes a short circuit. It saves if you use a battery. Because it uses energy only press the push button. See the advantages, do not wait! You can build it.
How it works
When we press the switch-S1. An electric current flows to the circuit. The IC1 will makes two things.
- First, generates a oscillator in high frequency. Which the C1 and R1 set a frequency level.
- Second, it will divide frequency to lower into the tones.
This audio signal from pin 7 and pin 4 into the pin 1 and pin 8 of the IC2a, IC2c respectively.
The IC2b of a frequency converter to control IC2c. When the control signal in during the low state (Low), The 1.25 kHz frequency will come to IC2a.
At the same time, the control signal flows through IC2b to be a high state (High).
The 300 Hz frequency will come to the IC2c. Also, the output at pin 3 of IC2a is low in the same condition.
The output of IC2a and IC2c output is sent to the IC2d. Which it mixes both signal to output to the transistor-Q1.
The Q1 acts as switches and amplifiers. The tones can be heard as two strokes.
The R3 acts as a volume.—You add more value to make the softer sound, but it is lower.
This circuit uses a 6V power supply. You should use a 6V battery or 1.5V x 4 batteries.
How to build this projects
You can build easily circuit with see in Figure 2. We use the universal PCB board because has a few parts Cause faster for make than general PCB.
The component List.
IC1_CD4060—14 stage ripple counter and oscillator IC
IC2 = CD4001—Quad 2-Input NOR(NAND) Buffered B Series Gate
Q1 = BC338—0.5A 50V NPN transistors.
S1 = Switch—nomally open pushbutton.
C1 = 0.0047uF 50V ceramic capacitors.
R1 = 47K Resistors
R2 = 4.7K Resistors
R3 = 2.2K Resistors
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